Pancreatin is obtained as an extract from animal pancreatic glands. Extracts of this type, which are obtained from biological raw material, can exhibit a high degree of viral contamination. Viruses are nucleic acids which are surrounded by a protein coat. Enveloped viruses also have an outer lipid envelope in addition. As viruses cannot replicate independently, they are dependent on hosts. Consequently, they are present in practically all living organisms on Earth. Very few of the known viruses are pathogenic for humans, as they have a high degree of host specificity. In order to rule out endangerment of the consumer from the beginning, extracts that are intended for human consumption or that are used as active agent in medicines should fundamentally have a viral contamination which is as low as possible or no viral contamination. It is not always the case that the actual production method leads to a significant inactivation or removal of the viruses present, so that, particularly when producing pharmaceutical active agents, additional reduction or inactivation steps must be integrated into the method.
Many methods are described for the reduction or inactivation of viruses and microorganisms [K. H. Wallhäuser, Praxis der Sterilisation Desinfektion Konservierung [Practice of Sterilization, Disinfection and Preservation], Thieme Verlag, Stuttgart 1995]. In addition to mechanical removal by e.g. chromatography or filtration, these contaminations can be inactivated selectively by the addition of chemical compounds. The latter method is however problematic insofar as these compounds must be completely removed again so that they do not cause any toxic effects in the end product. Physical methods such as e.g. heat treatment or irradiation are likewise well-established methods for inactivating viruses or microorganisms.
A particular challenge is the inactivation or removal of viruses from complex biological extracts whose active substance is enzyme mixtures, without destroying or changing the enzymatic activity of the proteins in the process.
Of particular economic interest is the pharmaceutical active agent pancreatin which is obtained as an extract from porcine pancreas and is used in dried form as an oral therapeutic agent, as described in German Patent DE 3248588 A1.
A known method for producing pancreatin is described hereinafter with reference to FIG. 1. The pancreatic glands 1 which came from domestic pigs are first comminuted 2 and subjected to autolysis 3. By filtering 4 the intermediate product obtained in this manner, the sieve filtrate is obtained 5. The enzymes which are present in the sieve filtrate are then precipitated 6, the mixture is filtered 7 and the filter cake is obtained 8. The filter cake obtained is finally ground 9, vacuum dried 10 and ground once more, whereby the pancreatin is obtained. The method steps designated with the reference numbers 2 to 10 in each case lead to intermediate products which are designated in the following as intermediate stages.
The active substances in pancreatin are various polymer-degrading enzymes such as lipases, amylases and proteases, amongst others. A prerequisite for the effectiveness of the therapy is that all enzymes are present in the active agent in a certain ratio and in active form.
Investigations into the viral contamination of pancreatin have shown that porcine parvovirus (PPV) is detectable as a single virus in pancreatin as an infectious particle. The zoonotic viruses EMCV, PEV9 and HEV and as well as rotavirus and reovirus could neither be detected as infectious particles nor at the genomic level. Fundamentally, pharmaceutical active agents should not contain any infectious viruses. Although, according to present knowledge, PPV is not pathogenic for humans, the goal should therefore be a PPV-free pancreatin. PPV is an oft used model virus as it stands out on account of a very high resistance to a wide range of inactivation methods. As the production process described in FIG. 1 is not in the position to completely remove the PPV contamination present, additional virus reduction steps must be implemented.
Classic virus inactivation methods, such as for example dry or wet heat, or virus reduction methods, such as for example filtration or chromatography, cannot be used in most cases for extracts from biological raw material and in particular for organ extracts without changing the composition and/or high product losses.
A method for producing a pancreatin-containing composition in dry powder form is known from U.S. Pat. No. 3,956,483, in which method chopped pancreas is mixed with an aqueous solution which contains calcium sulphate. An enzyme activator is then added to this mixture. After a predetermined period of time for the enzyme activation, the mixture is finally dehydrated, whereby pathogenic bacteria should be inactivated. This inactivation is carried out at temperatures above 160° F. (73° C.), preferably at 180° F. (82° C.). In all of the examples, an inactivation temperature of 82° C. is used.
U.S. Patent Application 2007/0148151 A1 discloses a method for producing pancreatin. To reduce the viral and bacterial contamination this method provides a heating of pancreatin in disperse form, to achieve this, the pancreatin should contain less than 9 weight % of one or a plurality of solvents. The examples show methods in which the proportion of the solvent was at least 1 weight %. The disperse pancreatin is then heated to a temperature of at least 85° C. for a period of time of less than 48 h.
Treatment at 85° C. or even higher temperatures is required according to US 2007/0148151 A1 in order to be able to fulfil the official regulations for virus contamination of biological products. At a temperature of 80° C., the regulations could not be fulfilled.
It is further stated in US Patent Application 2007/0148151 that a heat treatment at 60° C. for 70 hours can damage pancreatin. A heat treatment can destroy a substantial amount of the enzymatic activity of the pancreatin.
It is further known from the prior art that the results of a virus reduction by means of the action of heat depend to a considerable extent on the residual moisture of the samples. The dryer the material which is subjected to the heating, the higher is the resistance of the viruses to high temperatures. From this it follows that the temperature of the heating can be chosen to be lower, the higher is the residual moisture of the material.